Cobalt (II) Complexes Derived from Azo-Azomethine Ligands: Synthesis, Characterization, Solvatochromic, Fluorescence, Thermal, Electrochemical and Antimicrobial Properties

Three new cobalt (II) complexes were prepared by the condensation between the ligands, 1-{3-[(1-ethoxy-2-hydroxyethyl-imino)methyl]-4-hydroxyphenylazo}-4-nitro benzene (L-1), 1-{3-[(1-ethoxy-2-hydroxethyl-imino)methyl]-4-hydroxyphenylazo}-2-chloro- 4-nitrobenzene (L-2) and 1-{3-[(1-ethoxy-2-hydroxyethyl-imino)methyl]-4-hydroxyphenylazo}-4-chloro-3-nitrobenzene (L-3), with cobalt(II) acetate (molar ratio 1:1) in methanol as the solvent. These prepared cobalt (II) complexes were characterized by infrared, UV/Vis and fluorescence spectroscopy, elemental analysis and magnetic susceptibility measurements. The redox behavior of Schiff base ligands and cobalt (II) complexes determined using cyclic voltammetry technique. The solvatochromic behavior of the Schiff base ligands L-1-L-3 were recorded in three organic solvents with different polarity. On the basis of the UV/Vis and infrared spectra, the azo-azomethin ligands coordinated to the Co (II) ion through phenolic oxygen, alcoholic oxygen, etheric oxygen and imino nitrogen. The prepared ligands and their complexes be served as photoactive materials due to their intraligand (*) fluorescence. The effective magnetic moments of complexes CoL1, CoL2 and CoL3 are 3.95, 3.9 and 3.98 B.M., respectively that indicate these complexes have tetrahedral configuration. Thermal properties and decomposition behaviors of cobalt (II) complexes are reported by DTA/TG curves. Antibacterial activities of both ligands and complexes were studied.